Hawksbury Lagoon update Oct 2020

We have finally received the results of the autopsies on some of the ducks which died at the beginning of the year. The autopsy process, like everything else, was held up by the Covid lockdown in March. The report is rather inconclusive but I will quote the summary which I received from DOC.

“No obvious abnormalities were found on gross post mortem and the gizzard contained only grit. Unfortunately many toxins, including the botulism toxin and multiple algal toxins do not produce characteristic gross or histological changes to the internal organs” (Meaning that the internal organs showed no signs of disease or damage). “So essentially they were a male and female duck in good condition, with no obvious cause of death, which suggests that a toxin may be the cause”.

DOC were not willing to pay the additional cost of carrying out more extensive testing to ascertain if a specific toxin caused the deaths, however the pathologist has asked for fresh specimens to be sent to DOC if there should be another cluster of deaths in the future.

At the time of the deaths there was a lot of algae on the lagoon, also bread had been thrown into the water, either of which may have been consumed by the ducks, leading to their deaths. Botulism can also be held within the sediment and released when conditions are suitable ie low level water and heat. So at this time the cause of death of a number of birds in February continues to be unknown. Let’s hope that we don’t have another occurrence over the coming summer.

Shirley McKewen
Chair